I have been round in conditions like the first shots - lovely, what's all the fuss about...?
Also in conditions as per the photo above but in the dark - you don't really see the waves, only the spray just before it washes over you... ah, that's what all the fuss is about then!
I did a similar trip in a Fairline Targa 34 in Feb 2008 I think it was, from Brighton to our new berth in Torquay. We popped into Cowes to re-fuel en route. The conditions were poor and a bit choppy, particularly when we ran over St Albans ledge, but easily doable in one day. My passage plan is on my current boat, berthed in Spain, or I could provide better info.
Just make sure that you phone the naval/military firing range, we did just that, but they still called us on CH16 on the day to advise us we were half a cable from the target boat, which prompted the reply 'we have just increased our speed to 30 knots and will clear the area shortly' I was with John Mendez, well he said he had phoned them - it was great fun and we both enjoyed the trip!
I see myself as a relative novice too. I've done the trip in a Bayline 285 (single) and Sealine S34 (twin). We overnight at Poole and take the 5NM route, as others suggest. Personally I would go for F3 or less for your first trip.
There is no point in stressing yourself or your crew as I found out when I did the trip against a stiff F5. It was just a miserable trip really - but on the plus side we made it.